Hak, you are trying to strip away every reason why parents - may not want their child to sleep over at GP.
You have been given so many valid reasons and you say - thats all good and fine...I agree.
Then you keep repeating why GP who are of sound mind, kind, and have all normal relations cant have their GC over to stay.
Well....I am sure they do. I am sure right now, as I type there are thousands of rosy scenes with GC up stairs in bed, and GP downs stairs feeling all glowy and happy.
We know there are loads of us suffering tormented DILS on MN, we know that.
But we also know usually dils complain if there is a problem, so we can assume there are millions of very happy DILS and MILS out there - I do actually know some in RL, who all get on who dont mention it because they dont need too.
They have nothing to get off their minds.
So this repeating but what if great GP with GC why cant they sleep over is a non argument. There will be and equally millions of GP who adore and love their GC and still dont feel the need to put them to bed.